'On every other topic, the Pope pointed indirectly at the path he'd recommend. On climate change, he called Congress to do something concrete. But Congress has probably never been less likely to heed that call.'

'In short: No deal, Francis. When the pope first produced his climate encyclical, we offered skepticism that it would make a difference. That skepticism still holds, even after the pope's unprecedented personal appeal in front of the full federal representation of the United States. It was the only topic on which he broke from his preferred style of referring obliquely to the change he wanted to see. But that forcefulness by-Francis-standards isn't likely to make a dent at all.'

The last time Congress considered major legislation aimed at curtailing the greenhouse gas emissions that contribute to the warming climate was in President Obama’s first year in office. The proposal was a “cap and trade” bill that would have set limits on how much heavy carbon dioxide producers could emit and created a marketplace on which allowances for excess production could be traded. Your coal plant is producing more CO2 than it’s supposed to? Buy credits from a plant that is producing less than it’s allowed. The idea would set an overall amount of pollution — and provide market-based rewards for producing less. It’s a system similar to what was implemented to curtail acid rain under the administration of George H. W. Bush.

Thanks to a combination of the faltering economy, bad political choices and Republican opposition, the bill passed the House only to be abandoned in the (then-Democratic) Senate. In short order, the fight on Capitol Hill became about health care, and the topic faded.